The German Patent Application Publication No. 25 44 976 discloses such an apparatus for determining the mass throughput of pourable material, as lime dust or fine ore. The measurement is based on the effective inertia force, i.e. Coriolis force, caused by moving mass particles hitting a rotating reference body, as a measuring wheel comprising a rotating disk bearing radially extending guiding blades thereon, the pourable material being hurled off essentially vertical in respect of the axis of rotation. Changes in the driving torque are used as measurement value for determining the mass throughput which at constant angular speed of the measuring wheel is directly proportional to the measured torque. For detecting torque changes the known apparatus uses the power consumption of the driving motor.
Similar apparatuses are known from the German Patent Application Publications No. 33 46 145 and No. 39 40 576, where instead of measuring the power consumption of the driving motor the latter is supported pivotally or rotationally, respectively, and the reaction torque is directed to a laterally arranged load cell.
The known apparatuses based on measuring Coriolis forces are limited in throughput in view of the steep deflections by 90.degree. in the charging region of the measuring wheel and by almost 180.degree. in the discharging region of the guiding blades. In particular in connection with a pneumatic conveyance and high charging speeds there are caused uncontrolled bouncing effects onto the rotating measuring disk, detrimental for the measuring accuracy.
Furthermore, sticky materials easily tend to deposit on the measuring wheel, resulting in an unbalance thereof.